A private branch exchange (PBX) is a privately operated network which typically services the stations of a single business unit or other entity, for example a corporation or university campus. The PBX is connected via a direct inward dial (DID) trunk to a switching system of the wireline network. The PBX itself is a private self-regulated switching element that commonly provides its users/subscribers with features like those found in public networks. Calls that are made to a PBX station from the public wireline network, such as the Public Switched Telephone Network (PSTN), are routed to a "Class 5" switch serving that PBX. The Class 5 switch routes the calls over PBX trunks to the PBX for termination to the stations served by the PBX. When a PBX user originates a call to the PSTN, the user typically dials an access digit such as "9" and the called party's telephone number. The call is then forwarded to the Class 5 switch in the PSTN for termination to the called party. Internal calls among stations served by the PBX are processed internally to the PBX. The PBX is also capable of providing such features as abbreviated dialing, call forwarding, call transfer, etc., to the PBX stations.
In the PBX architecture, equipment is available to the business customer allowing it to provide wireless access to its users. A Class 5 switch, such as a Service Switching Point (SSP), serves a PBX via a plurality of PBX trunks. PBX allows users to use a PBX extension telephone.
Currently, because the PBX network is a privately operated system, it is not served by either the public wireline or wireless networks. Likewise, the PBX cannot access the services available to subscribers in the public wireline and wireless networks, nor does the PBX have access to the public network's AIN architecture capabilities. Moreover, once a call is handed off to the PBX network, there is little opportunity to hand it back to the public network for processing.
This lack of interworking capability between private, wireline and wireless systems introduces several drawbacks. These drawbacks include the lack of call handling provisions for calls directed from the public wireline and wireless networks to private networks such as PBX. As PBX networks become more common as these business units seek a cost-savings by operating their own communication systems, PBX networks are not capable of providing or accommodating services that presently exist among and between public wireline networks and wireless networks.
Consequently, a need has developed for a system and method which provides for an integrated wireline-wireless services which utilizes PBX lines and provides the capability for calls directed to PBX networks to be processed via the public networks prior to their handoff to the PBX network.